OK Let's assume I have the Gentoo i386 package installed on my hard-drive.
Now I want to run my C-Code on an ARM processor using the Serial RS-232 port.
Does Gentoo support this? because I've known PCQ Linux 2k4 and Red Hat to support this...

OK Let's assume I have the Gentoo i386 package installed on my hard-drive.
Now I want to run my C-Code on an ARM processor using the Serial RS-232 port.
Does Gentoo support this? because I've known PCQ Linux 2k4 and Red Hat to support this...

If I understand you correctly, this is not a Gentoo issue but a gcc issue.

You're compiling your own personal code, so if gcc has support for the processor you are targeting and the needed libraries, if needed, are available on the ARM based machine, should be no issue.